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가스터빈 블레이드 온도 특성 및 코팅층 건전성 평가를 위한 적외선 열화상 카메라 기법 활용
김재열,심재기,최승현,최진호 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
Key part of main equipment in a gas turbine may be likely to be damaged due to operation under high temperature, high pressure, high-speed rotation, etc. Accordingly, the cost for maintenance increases and the damaged parts may cause generation to stop. The number of parts for maintenance also increases, but diagnostics technology for the maintenance actually does not catch up with the demand. Blades are made of precipitation hardening Ni superalloy IN738 and the like for keeping hot strength. The surface of a blade is thermal-sprayed, using powder with main compositions such as Ni, Cr, Al, etc. in order to inhibit hot oxidation. Conventional regular maintenance of the coating layer of a blade is made by FPI(Fluorescent Penetrant Inspection) and MTP(Magnetic Particle Testing). Such methods, however, are complicated and take long time and also require much cost. In this study, defect diagnostics were tested for the coating layer of an industrial gas turbine blade, using an infraredthermography camera. Since the infrared thermography method can check a temperature distribution on a wide range of area by means of non-contact, it can advantageously save expenses and time as compared to conventional test methods. For the infrared thermography method, however, thermo-load must be applied onto a tested specimen and it is difficult to quantify the measured data. To solve the problems, this essay includes description about producing a specimen of a gas turbine blade (bucket), applying thermo-load onto the produced specimen, photographing thermography images by an infrared thermography camera, analyzing the thermography images, and pre-testing for analyzing defects on the coating layer of the gas turbine blade.
임신기간중 혈장 Fibronectin 농도변화를 이용한 임신성 고혈압 발생의 예측 가능성에 관한 연구
정두용,최종현,최경남,김민철,승경록 건국대학교 의과학연구소 1995 건국의과학학술지 Vol.5 No.-
Preeclampsia is classically defined as the triad of pregnancy induced hypertension(PIH) with generalized edema and proteinuria, and constitutes a deadly triad of maternal death. Recent studies suggest that drugs affecting prostacyclin and thromboxane production may be able to affect the development of preeclampsia(PE). In order to use these agents effectively, a woman at high risk should be selected properly before the clinical illness manifests. As the pathophysiologic mechanism of PE., endothelial damage is thought to play a major role in these days. Many investigators have suggested that plasma fibronectin(FN), a good indicator of vascular endothelial damage, is markedly elevated at least 4 weeks before clinical manifestations of PE and can be used as a sensitive predictor of PIH. To assess the clinical utility of plasma FN in predicting PIH, plasma FN concentrations of pregnant women over 28 weeks of gestation who visited Kon-Kuk University Hospital from June 1, 1994 to February 28, 1995 were assayed. The results were as follows: among 108 pregnancy specimens, 70 were in the normal blood pressure group and 38 were PIH group: 20, transient hypertension subgroup(PH), 8, mild PE subgroup(PM), 10, severe PE subgroup(PS). There was statistical significance in the mean birthweight between normal blood pressure group(3,205±68g) and PS subgroup(2,455±315g) (p<0.05). The mean concentrations of plasma FN were highest in the PS subgroup(412±68.9ug/㎖) and lowest in the normal blood pressure group(244±8.7ug/㎖), that is stastically significant. Plasma FN concentration in the normal pregnancy period showed fluctuation: from 29 weeks of gestation to 36 weeks, elevation and after 36 weeks, decline. The changes in the mean concentrations of plasma FN after delivery were noted in both groups, but those in normal blood pressure group(254±13→227±10㎍/㎖) and PS(405±22→318±51㎍/㎖)were stastically significant(p<0.05). There was negative linear correlation between the platelet count and concentration of plasma FN in the PS group [platelets(Y)=-0.20192×FN(X)+262.23257 r=0.69] (p<0.05). There was no linear correlation between the birthweight and plasma FN concentration in normal blood pressure group and PIH group. The changes in the plasma FN concentration in the normal blood pressure group and PIH group before clinical manifestation were not statistically significant.
Song, Y.B.,Hahn, J.Y.,Yang, J.H.,Choi, S.H.,Choi, J.H.,Lee, S.H.,Jeong, M.H.,Kim, H.S.,Lee, J.H.,Yu, C.W.,Rha, S.W.,Jang, Y.,Yoon, J.H.,Tahk, S.J.,Seung, K.B.,Oh, J.H.,Park, J.S.,Gwon, H.C. Elsevier 2014 JACC. Cardiovascular interventions Vol.7 No.3
Objectives: The authors sought to investigate whether the impact of treatment strategies on clinical outcomes differed between patients with left main (LM) bifurcation lesions and those with non-LM bifurcation lesions. Background: Few studies have considered anatomic location when comparing 1- and 2-stent strategies for bifurcation lesions. Methods: We compared the prognostic impact of treatment strategies on clinical outcomes in 2,044 patients with non-LM bifurcation lesions and 853 with LM bifurcation lesions. The primary outcome was target lesion failure (TLF) defined as a composite of cardiac death, myocardial infarction (MI), and target lesion revascularization. Results: The 2-stent strategy was used more frequently in the LM bifurcation group than in the non-LM bifurcation group (40.3% vs. 20.8%, p < 0.01). During a median follow-up of 36 months, the 2-stent strategy was not associated with a higher incidence of cardiac death (hazard ratio [HR]: 1.24; 95% confidence interval [CI]: 0.72 to 2.14; p = 0.44), cardiac death or MI (HR: 1.12; 95% CI: 0.58 to 2.19; p = 0.73), or TLF (HR: 1.39; 95% CI: 0.99 to 1.94; p = 0.06) in the non-LM bifurcation group. In contrast, in patients with LM bifurcation lesions, the 2-stent strategy was associated with a higher incidence of cardiac death (HR: 2.43; 95% CI: 1.05 to 5.59; p = 0.04), cardiac death or MI (HR: 2.09; 95% CI: 1.08 to 4.04; p = 0.03), as well as TLF (HR: 2.38; 95% CI: 1.60 to 3.55; p < 0.01). Significant interactions were present between treatment strategies and bifurcation lesion locations for TLF (p = 0.01). Conclusions: The 1-stent strategy, if possible, should initially be considered the preferred approach for the treatment of coronary bifurcation lesions, especially LM bifurcation lesions. (Korean Coronary Bifurcation Stenting [COBIS] Registry II; NCT01642992)
Choi, Seokjin,Kim, Du Y.,Han, Seung H.,Kwak, Young Hoon American Society of Civil Engineers 2014 Journal of construction engineering and management Vol.140 No.1
<P> Long-term transportation policies require government officials to predict the cost of public road construction during the conceptual planning phase. However, early cost prediction is often inaccurate because public officials are not familiar with cost engineering practices, and moreover, have limited time and insufficient information for estimating the possible range of the cost distribution. This study develops a conceptual cost prediction model by combining rough set theory, case-based reasoning, and genetic algorithms to better predict costs in the conceptual planning phase. Rough set theory and qualitative in-depth interviews are integrated to select the proper input attributes for the cost prediction model. Case-based reasoning is then applied to predict road construction costs by considering users’ difficulties in the conceptual policy planning phase. A genetic algorithm is also used to assist the rough set model and case-based reasoning model to obtain optimal solutions. The result of the analysis shows that the proposed conceptual cost prediction model is reliable and robust compared to the existing cost prediction model.</P>
Effect of crotonaldehyde on the induction of COX-2 expression in human endothelial cells
Seung Eun Lee,Hye Rim Park,Hyemi Kim,Yeoum Choi,Young-Ho Jin,Cheung-Seog Park,Hyun-Jong Ahn,Jeong-Je Cho,Yong Seek Park,Y. S. Park 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.3
Cyclooxygenase-2 (COX-2), an inducible isoform protein, regulates diverse biological actions in vascular pathophysiology. COX-2 is induced in response to numerous stimuli, which results in prostaglandin (PG) production related to inflammation. Crotonaldehyde (CRA) is an extremely toxic α, β-unsaturated aldehyde and a major compound found in cigarette smoke. α, β-Unsaturated aldehyde in cigarette smoke is thought to mediate inflammation and vascular dysfunction. In this study, we evaluated the effect of CRA stimulation on COX-2 expression in human umbilical vein endothelial cells. CRA-stimulated COX-2 induction was accompanied by enhanced p38 phosphorylation and PGE2 generation. However, CRA-induced PGE2 production was reduced by pretreatment with an inhibitor of p38 MAPK. These results demonstrated that in human endothelial cells, CRA-induced COX-2-dependent PGE2 generation was mediated by p38 MAPK, and CRA may play a role in the development of inflammation.
Polymer Thin Film–Induced Tumor Spheroids Acquire Cancer Stem Cell–like Properties
Choi, Minsuk,Yu, Seung J.,Choi, Yoonjung,Lee, Hak R.,Lee, Eunbeol,Lee, Eunjung,Lee, Yumi,Song, Junhyuk,Son, Jin G.,Lee, Tae G.,Kim, Jin Y.,Kang, Sukmo,Baek, Jieung,Lee, Daeyoup,Im, Sung G.,Jon, Sangyo American Association for Cancer Research 2018 Cancer Research Vol.78 No.24
<P>A new cell culture technology enables highly tumorigenic 3D spheroids to be easily generated from various cancer cell sources in the common laboratory.</P><P><B></B></P><P>Although cancer stem cells (CSC) are thought to be responsible for tumor recurrence and resistance to chemotherapy, CSC-related research and drug development have been hampered by the limited supply of diverse, patient-derived CSC. Here, we present a functional polymer thin film (PTF) platform that promotes conversion of cancer cells to highly tumorigenic three-dimensional (3D) spheroids without the use of biochemical or genetic manipulations. Culturing various human cancer cells on the specific PTF, poly(2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane) (pV4D4), gave rise to numerous multicellular tumor spheroids within 24 hours with high efficiency and reproducibility. Cancer cells in the resulting spheroids showed a significant increase in the expression of CSC-associated genes and acquired increased drug resistance compared with two-dimensional monolayer-cultured controls. These spheroids also exhibited enhanced xenograft tumor-forming ability and metastatic capacity in nude mice. By enabling the generation of tumorigenic spheroids from diverse cancer cells, the surface platform described here harbors the potential to contribute to CSC-related basic research and drug development.</P><P><B>Significance:</B></P><P>A new cell culture technology enables highly tumorigenic 3D spheroids to be easily generated from various cancer cell sources in the common laboratory.</P>